genetic and neural explanations of OB Flashcards
what are the different components of the genetic explanation
twin studies (inc adoption studies)
diathesis stress and epigenetics
candidate gene studies
what do genetic exps assume: that criminality is the result of …
an inherited characteristic
proposing that one or more genes predispose individuals to criminal B
what are the examples of twin studies
lange
christiansen
raine
lange twin study: investigated … MZ and …. DZ twins, where one of the twins…
they then explored how many of them…
and what did they find and what does this conclude
13mz
17dz
where one of the twins in each pair had served time in prison
and then explored how many of them had a co-twin who had also spent time in prison (concordance rate)
found no with cotwin in prison:
10 for mz
2 for dz
therefore suggests that genetic factors must play a predominant role in OB AND the more genes shared the more similarity in conviction
what are limitations of lange’s twin study
the sample size is small and so there is a lack of generalisability
they judged whether the twins were mz/dz based off appearance and not off a dna test and so this could lead to a lack of validity. (there are some mz twins who dont look the same and so could be thought of as dz)
christiansen explored the concordance rate of offending in mz and dz twin pairs
they had …. mz pairs and …. dz pairs
concordance rates were…
and what does this support the view of…
but what is the problem with these results
87 mz pairs , ccr = 33%
147 dz pairs, ccr = 12%
supports he view that OB may have a genetic component
BUT you would expect mz twins to have a higher if not 100% ccr and so this suggests that other factors have a role and it isnt due to genetics entirely
raines twin evidence, raine reviewed delinquent B of twins and found what ccr for mz and dz
what are limitations of this
mz ccr- 52%
dz ccr- 21%
delinquent b is very broad and so this was not operationalised, so the difference in rates could be due to type of delinquency/how it was measured, delinquent not necessarily convicted so the difference could be due to convicted vs not
the sample was also very small so cant necessarily generalise
what are general lims of twin studies: cant separate
the role of genetics and the E and MZ have a more similar E and so this doesnt represent how others see the world, dz because they look different they may be treated different and so that could be a reason the ccr was less as they have more different experiences
what are the examples of adoption studies
crowe
mednick
mednick studied … adoptees and looked at their risk of OB
what was the % of adopted sons who went on to be criminals
with both adoptive and bio parents having criminal convictions: 24.5%
bio crim parents- 20%
crim ad parents- 15%
neither bio nor ad parents had criminal convictions- 13.5%
what are lims of mednick
they didnt look at daughters and so by not separating this is could act as confounding variable, ie results could be because sons offend more than daughters.
only petty crime was studied so cant generalise to serious crime
what did crowe find- adoption study
adoptees risk of having a criminal record by age 18 for having either a biological or adoptive parent with a criminal record
biological- 50% greater risk
adoptive- 5% risk
suggests that inherited genes are a marginally more significant factor than E influences
what are the lims of adoption studies
adoption could happen at any ages, the reason for adoption could be because the parent is in prison, could still be eg visiting biological parent, more traumatic when older »_space; E factors
cant separate all factors so assumes the role of genetics and the E
what are the components of the neural exp of OB
regions of the brain
mirror neurones
neurotransmitters
what is APD
antisocial personality disorder (formerly psychopathy) and most evidence for neural exp comes from offender with ADP.
characterised by lack of empathy, reduced emotional responses, and it characterises many criminals
what is the evidence regions of the brain: raine cited … brain imaging studies showing …
also raine found …% reduction in
prefrontal cortex
71 showing offenders (murderers, psychopaths, violent individuals) have decreased functioning in the prefrontal cortex
11% reduction in volume of grey matter in prefrontal cortex of people with APD compared to controls
what is the prefrontal cortex involved in
regulating emotion and controlling moral B, a decrease in activity = impulsiveness and loss of control
what is the evidence regions of the brain: raine found that … who were found ….
limbic system
murderers who were found not guilty by insanity, compared to control, were found to have abnormal asymmetries in limbic system, especially the amygdala having reduces activity on the left and increased on the right
what is the limbic system responsible for
it is a set of subcortical structures including the hypothalamus, amygdala. it is linked to emotion and motivation
what are mirror neurones
an exp that says that criminals with APD can exp empathy but more sporadically then everyone else
christian keysers found that criminals could empathsise when asked to (when shown a video of a person in “pain”) and this activates an empathy reaction suggesting APD can have a neural switch controlled by mirror neurones whereas a normal brain has empathy permanently on
what is the evidence for neurotransmitters: serotonin, seo suggested that ..
low serotonin levels predispose individuals to impulsive aggression > ob, this is because low S > lack of inhibition of impulsive aggressive urges by the prefrontal cortex
dopamine hyperactivity may enhance this effect
what is the evidence for neurotransmitters: noradrenaline
very high OR very low noradrenaline levels is associated with aggression, violence and criminality (Wright)
very high: causes activation of the sns and the f/fr which leads to aggression
very low: reduces ability to react to perceived threats
